This frequency divider by 10 uses discrete components only. Modern equivalent components can be used as the circuit is from an 80's documentation. Nearby frequencies can be used.
This circuit uses common diodes as sensors, triggering when the temperature rises by touch,...
Simple timers can be designed using inverters or any other gate that can be connected as inverter. Figure...
This circuit was found in the 1987 Radio Electronics magazine. The components used are integrated...